From 1ca4264ee17745779c341966c5e61ac69bfd17a6 Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Wed, 9 Apr 2008 15:24:22 +1000 Subject: [PATCH] [POWERPC] spufs: fix save of mfc_cntl register Currently, we can introduce invalid entries into the MFC queues: 1) context starts a DMA 2) context gets scheduled out during a DMA - kernel saves MFC queue to CSA - kernel saves 0x0 in csa->mfc_control_RW 3) context gets scheduled in - csa->mfc_control[Q] ('queues empty') isn't set, so DMA queues are restored from the CSA 4) context's DMA is completed 5) context gets scheduled out again, no DMA occuring this time - kernel sees that MFC_CNTL[Q] ('queues empty') is set, so doesn't touch saved queue data in CSA - kernel saves 0x0 in csa->mfc_control_RW 6) context gets scheduled in - csa->mfc_control[Q] ('queues empty') isn't set (we saved is as 0!), so DMA queues are restored from the CSA In this last restore, we've restored the queue status from step 2, which are now invalid. This change makes save_mfc_cntl() closer to the save/restore sequence, as specified in the CBE handbook. With changes from Luke Browning. Signed-off-by: Jeremy Kerr --- arch/powerpc/platforms/cell/spufs/switch.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/platforms/cell/spufs/switch.c b/arch/powerpc/platforms/cell/spufs/switch.c index 65b423b6da48..4131784216bb 100644 --- a/arch/powerpc/platforms/cell/spufs/switch.c +++ b/arch/powerpc/platforms/cell/spufs/switch.c @@ -186,20 +186,21 @@ static inline void save_mfc_cntl(struct spu_state *csa, struct spu *spu) MFC_CNTL_SUSPEND_COMPLETE); /* fall through */ case MFC_CNTL_SUSPEND_COMPLETE: - if (csa) { + if (csa) csa->priv2.mfc_control_RW = - MFC_CNTL_SUSPEND_MASK | + in_be64(&priv2->mfc_control_RW) | MFC_CNTL_SUSPEND_DMA_QUEUE; - } break; case MFC_CNTL_NORMAL_DMA_QUEUE_OPERATION: out_be64(&priv2->mfc_control_RW, MFC_CNTL_SUSPEND_DMA_QUEUE); POLL_WHILE_FALSE((in_be64(&priv2->mfc_control_RW) & MFC_CNTL_SUSPEND_DMA_STATUS_MASK) == MFC_CNTL_SUSPEND_COMPLETE); - if (csa) { - csa->priv2.mfc_control_RW = 0; - } + if (csa) + csa->priv2.mfc_control_RW = + in_be64(&priv2->mfc_control_RW) & + ~MFC_CNTL_SUSPEND_DMA_QUEUE & + ~MFC_CNTL_SUSPEND_MASK; break; } } -- 2.20.1